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Meeting future water demand will require serious consideration of direct potable reuse (DPR) for many water agencies. There has been tremendous progress in the technologies needed to address the concerns that conventional and novel water contaminants pose. Yet, to date, only a few relatively small DPR operations have been installed. As we get closer to the point where regulations are finalized and serious investments are planned, there is a need to ask: Are we ready? In this Review, we explore the technological, economic, and environmental considerations associated with DPR. In particular, we focus on the status of technologies for addressing the most challenging water pollutants, the cost estimates for DPR, and the energy demand and associated implications of DPR. We find that, although the technologies are nearly ready for DPR, the most critical issue will be real-time monitoring of a number of molecules that pose distinct challenges to advanced treatment trains. In addition, there is a need to consider emergency planning, both in terms of emergency buffer reservoir(s) and planning for situations in which the treated water does not meet specifications. Since any advanced treatment train will result in a significant increase in embedded energy, it will be particularly important to plan for renewable energy to minimize environmental impacts.
Keller et al. (Thu,) studied this question.